Intake systems including manifolds for connecting one or more carburetors to a multi-cylinder internal combustion engine are well known. Typically, an air-fuel mixture is provided to the cylinders via the intake manifold. A common goal of many intake systems is to get as much air-fuel mixture into the cylinders as possible.
In a typical intake system, when a cylinder intake valve is open, the air-fuel mixture is pushed by atmospheric pressure into the engine causing the mixture to be rapidly be pushed through the intake manifold toward the combustion chamber. When the intake valve suddenly closes, this forward flow slams to a stop, resulting in high-pressure reverse flow. This high back pressure or reverse flow/wave makes its way up the intake manifold away from the intake valve typically back toward the carburetor.
This back pressure, or reverse flow, is actually a series of reverse pulses or shock waves that enter the intake tract when the intake valve or other means controlling the flow of the intake charge into the combustion chamber closes. The reverse impulse flow causes some of the forward flow to be slowed stalled or even reversed. In some engines, such as motorcycle engines when the cleaner is removed for example, the reverse impulse flow travels back through the carburetor and sprays the fuel and air mixture on the rider's leg. During idle, this reverse impulse flow is typically not severe enough to significantly affect engine performance or cause fuel spray through the carburetor. However, as the carburetor throttle is more fully opened, the amount and intensity of the fuel mixture flow is increased, and the amount and intensity of the reverse impulse flow accordingly is increased.
Detrimental effects of the reverse impulse flow are usually more severe in high performance internal combustion engines (e.g., motorcycle engines). However, motors of all types, including those utilizing piston porting, conventional valves, reed valves, and also rotary valves used for controlling communication between the intake tract and combustion chamber have a reverse flow problem.
Thus, a system capable of reducing the detrimental effects of reverse impulse flow is desired.